There is a dedicated battery measuring instrument for the judgment of the quality of the battery, but the average user rarely has this kind of instrument, and there is only a multimeter. The following points are summarized in the maintenance of the battery to judge the quality of the battery for reference. 1, from Appearance Judgment: Observe whether the appearance is deformed, bulging, leaking, cracked and exploded, burnt, and whether there is oxide seepage at the screw connection, etc. 2. Load measurement: If there is no abnormal appearance, the UPS works in battery mode with a certain amount of load. If the discharge time is significantly shorter than the normal discharge time, after 8 hours of charging, the normal standby time cannot be restored, and the battery is judged to be aging . 3. Measure with a multimeter: A. Measure in battery discharge mode: measure the voltage of each battery terminal in the battery pack, if one or more of the battery terminal voltages are significantly higher or lower than the nominal voltage (nominal voltage 12V/cell), Determine the aging of the battery. B. Measurement in mains mode: The charging voltage of each battery terminal in the battery pack. If the charging voltage of one or more of the batteries is significantly higher or lower than other voltages, the battery is judged to be aging. C. Measure the total voltage of the battery pack: the total voltage of the battery pack is obviously lower than the nominal value (take the nominal value of the C1K battery pack as an example), and it cannot be restored to the normal value after 8 hours of charging, even if it returns to the normal value, If the discharge time does not reach the normal discharge time, the battery is judged to be aging. D. Battery power-on measurement: The UPS is not turned on, and do not connect to the mains. Use a multimeter to measure the total voltage of the battery pack. Take C1K as an example. At this time, the voltage may be between 36V-40V, which is a normal value. Stare at the instructions of the multimeter, and then turn on the power button. If the total battery voltage drops below 30V or even more than ten volts at this time, the UPS will automatically shut down immediately, and the voltage will immediately return to its original value after shutting down. Determine the battery aging.